Machines that utilize buoyancy and gravity to generate power have been described. For example, the U.S. Pat. No. 4,718,232 titled “Gravity and buoyancy driven power generators,” teaches an apparatus with a long chain having an attached hollow body that passes through a rotating sprocket, which generates electrical power.
Another patent titled “gravity generating system” (U.S. Pat. No. 5,905,312) teaches a system that includes a plurality of tanks mounted on a circulating device. When the tanks receive the working medium descending from a higher place elevation, the circulating device is driven to circulate among a guidance device so as to drive a working shaft of a generator to produce electricity. A transmission mechanism is added between the circulating device and the working shaft to increase the rotational speed of the working shaft.
U.S. Pat. No. 3,412,482 discloses a buoyancy demonstrating apparatus wherein a plurality of expansible and compressible gas chambers is provided around the periphery of an endless carrier that is immersed in water.
U.S. Pat. No. 3,194,008 is for a “positive buoyancy prime mover” employing a device is submerged in a liquid and harnessing rotary motion derived from the buoyancy of a plurality of balls mounted at the end of spokes extending out from a central hub.
International application Publication No. WO2007007114A1 teaches buoyant systems in which objects are raised to an elevated height by buoyancy in a liquid and are then transferred to a receiving device operable to lower the objects by the force of gravity. The receiving device is provided with a power-take off device for generating electricity or operating mechanical devices. The objects are introduced into a depressurized air lock chamber and a pressuring gas introduced to equalize the pressures in the air lock chamber and a pressure chamber communicating with the lower end of the tower such that the objects are inserted into the lower end of the tower via the pressure chamber. In this case, the function is achieved by a chain and pressure air lock chamber.